From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 1/2] net: Toeplitz library functions Date: Tue, 24 Sep 2013 14:49:06 -0400 (EDT) Message-ID: <20130924.144906.781831317299527167.davem@redhat.com> References: <20130924.140312.1944338200709799169.davem@redhat.com> <1380046245.2736.52.camel@bwh-desktop.uk.level5networks.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: therbert@google.com, David.Laight@aculab.com, netdev@vger.kernel.org, jesse.brandeburg@intel.com To: bhutchings@solarflare.com Return-path: Received: from mx1.redhat.com ([209.132.183.28]:24444 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754161Ab3IXStQ (ORCPT ); Tue, 24 Sep 2013 14:49:16 -0400 In-Reply-To: <1380046245.2736.52.camel@bwh-desktop.uk.level5networks.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Ben Hutchings Date: Tue, 24 Sep 2013 19:10:45 +0100 > On Tue, 2013-09-24 at 14:03 -0400, David Miller wrote: >> From: Tom Herbert >> Date: Tue, 24 Sep 2013 08:54:24 -0700 >> >> > On Tue, Sep 24, 2013 at 8:39 AM, David Miller wrote: >> >> From: Tom Herbert >> >> Date: Tue, 24 Sep 2013 08:22:55 -0700 >> >> >> >>> We use this value for steering, and could use it for other uses like >> >>> connection lookup. >> >> >> >> For security reasons we absolutely cannot use it for that purpose, >> >> please stop claiming this. >> >> >> >> Any hash function which an attacker can reproduce is attackable. >> > >> > The Toeplitz function uses a secret key whose length is based on the >> > input length. 96 bits in IPv4, 320 bits in IPv6. I don't see how an >> > attacker can reproduce this if the key is random. If the problem is >> > that devices are not being configured with a sufficiently random key >> > (some actually are using a fixed key :-( ), that's a separate issue >> > that should be addressed. It is possible to DoS attack through the >> > steering mechanism. >> >> All of them are using a fixed, defined, key. > > This is certainly false, as I know sfc randomises the key. And the > Microsoft RSS spec appears to require that the key is programmable. Then I stand corrected.